1. Field of the Invention
This invention relates to an improved process for producing by a simple treatment micro-bends carbonaceous structure and particularly having a graphite cyrstalline structure which are useful as a raw material for high density isotropic carbonaceous materials as well as to a process for producing a high density isotropic carbonaceous structure from said micro-beads.
2. Description of the Prior Art
When a pitch, such as coal tar pitch and petroleum pitch, is heated, formation of optically anisotropic spherules having a diameter of about one micron to several tens of microns is observed when the heating temperature is about 350.degree.-450.degree.C. On further heating, these spherules gradually grow and coalesce with one another until the pitch is finally wholly anisotropic. When the temperature reaches about 500.degree.C, the pitch is completely solidified and changed to coke.
These spherules assume a spherical form since the high molecular weight condensed polycyclic aromatic compound formed by pyrolysis and thermal polymerization of the pitch is oriented in a determined direction to form a lamella which is then laminated spherically. Thus, each spherule is a kind of liquid crystal droplet. As the crystal structure of such spherules is the same as that of graphite, these spherules can be considered to be a precursor for graphite crystal. Therefore, if it is possible to separate these spherules from the pitch matrix in which they are formed and then carbonize the spherules while retaining their crystal structure, one would expect to obtain micro-bends containing graphite crystal. On the basis of such thinking, there was proposed a process in which the surface of spherules separated from a pitch is coated with a resin or subjected to an oxidation treatment so as to prevent the spherules from undergoing mutual coalescence and then the treated spherules are subjected to a carbonization treatment (see Japanese Published Pat. Appln. No. 4513/Sho. 46).
However, the carbonized product obtained by this process has some disadvantages in that deterioration of the graphitizing property of the spherules caused by contamination with impurities and non-homogeneity of the components cannot be avoided. In addition, a high density carbonaceous material cannot be obtained from the carbonized product.